Research On Dual-function A₃Sb₂X₉ Optoelectronic Devices For Self-powered Photodetection And Indoor Photovoltaics

Sustainability is the inevitable requirement of the increasingly rapid revolution of the Internet of things（IoTs）.Self-powered photodetection and indoor photovoltaics to supply power for IoT devices are two feasible strategies.With the consideration of facile and low-cost fabrication,emerging antimony-based perovskite derivatives have intensive potential due to their substitution of toxic lead while maintenance of superior optoelectronic properties to lead-based perovskites,such as high absorption coefficient,similar electronic structure,analogous polarizability.On the premise of electric neutrality,Sb-based perovskites have the A₃Sb₂X₉ general formula and two possible crystal structures--0D dimer type and 2D layered type.So far,there has been a blank for self-powered photodetection and indoor photovoltaic performance in Sb-based perovskite photodevices,as well as the effect of crystal dimensionality.To this regard,detailed discussion on two aforementioned applications and reliable characterization of intrinsic defect levels in 0D-Cs₃Sb₂I₉,2D-Cs₃Sb₂I_9-xCl_x and 2D-Rb₃Sb₂I₉ will be provided in this thesis.1.Compared to the 0D counterparts,as-prepared 2D layered A₃ Sb₂X₉ films with expected crystal dimensionality exhibit their advantages in light absorption,optical bandgap,reduced exiton self-trapping and effective carrier lifetime observed by optical,PL and TRPL spectra.These performances also directly result in their excellent performances of the corresponding self-powered photodetectors.Especially,2D-Cs₃Sb₂I_9-xCl_x devices deliver a more-than-tenfold increase in EQE（55%）,fast speed of response（ttr≈l5μs and f3dB>5KHz）,linear dynamic range over four orders of magnitude（and expected to 190dB）in self-powered operation,compared to previous self-powered A₃B₂X₉ implementations.Device stability under N₂ storage and photostability measurements reveal Sb-based perovskite derivatives are quite stable,while 2D devices are also more stable in photoconversion performance disclosed by tracking normalized EQE spectra for 600h.2.We deeply investigate the indoor photovoltaic performance of two representative 2D layered perovskite derivatives,Cs₃Sb₂I_9-xCl_x and BiOI.Because of their EQE spectra greatly overlapped with indoor light spectra,their efficiencies increase to 4-5%indoor PCEs from circa 1%under 1-sun illumination.These efficiencies are within the range of reported values for industrially standard hydrogenated amorphous silicon indoor photovoltaics.Future optimization approaches are put forward for improvements in efficiency after intensity-dependent measurements and optical loss analyses.Additionally,55%and 44%optically limited indoor efficiencies can be theoretically reached in 2D-Cs₃Sb₂I_9-xCl_x and 2D-BiOI,respectively.3.We finally have a deep insight into the defect levels of antimony-based perovskite derivaties via photoinduced current transient spectroscopy technology.The results show that all types of materials exhibit double defect characteristics with specific quantification of defect parameters,such as energy depth,caputure cross-sectional area and corresponding coulomb properties.This research highlights the wide-bandgap lead-free antimony-based perovskite derivative materials have attractive optoelectronic properties and stable performance,which provides a promising direction for the development of next-generation environmentally friendly and sustainable IoT devices;it also encourages researchers to regard self-powered photodetectors and indoor photovoltaics as a key target area in the future exploration of these materials.